Recently, I've been doing a lot of yard work and as a consequence my hands are covered with wounds and Band-Aids. Plus a flea jumped onto my knee yesterday. Perhaps it's not surprising that the subject of bloodletting popped into my mind.
Of course, many people know that in centuries past doctors and barber-surgeons used to "bleed" their hapless patients to help balance the body's humors (phlegm, blood, yellow and black bile). Bloodletting--be it with the aid of a leech or nasty-and sharp-sounding instruments like the "spring-loaded lancet," "scarificator" and "fleam"--was just one of several methods (including vomiting and purging) employed to achieve this delicate balance. It was purported to cure everything from melancholia to fever--even hemorrhage. (This last one seems a bit of a stretch.)
You had to watch out when and where you stuck people, though, according to old bloodletting charts. Astrology held that different parts of the body were ruled by different zodiac signs; these parts were to be avoided at certain phases of the moon.
As late as 1833, bloodletting was still so popular in Europe that more than 40 million (!) leeches were imported into France for the purpose. But by the 20th century, the leech industry had crashed and bloodletting was relegated to the status of quackery.
That is, for the most part. Some people really do benefit from bloodletting (or therapeutic phlebotomy, as it's termed nowadays). This we learned from blood maven Dr. Donald Feinstein, a USC professor of medicine and hematology.
Some people, he tells us, absorb too much iron, often as a result of a genetic condition called hereditary hemochromatosis. Over the years, the extra iron builds up slowly in people's bodies, causing damage to organs such as the liver and heart as well as the joints.
What contains a lot of iron? Red blood cells! That's what. Thus, the therapy for iron overload (as it's also called) is to draw pint after pint of blood from patients until the iron stores drop to an acceptable level, and thereafter draw the occasional unit of blood so those levels don't creep up again.
Getting rid of blood also helps people with a disease called polycythemia rubra vera. The bone marrow in such folks is working overtime, and the blood gets way too thick--putting these people at risk for clots and strokes. Phlebotomy helps thin things down.
Phlebotomy can also help people who are cranking out extra red cells because their bodies are starved of oxygen--because they've got some heart or lung problem, say. But it's a tricky balance with patients like that, Feinstein says: You don't want to take so much blood that you exacerbate their oxygen problems.
Other patients get only part of their blood taken out. ("There's phlebotomy and phlebotomy," Feinstein notes.) The clear stuff--the plasma--can get thick and gooey under some medical circumstances. To help, you take out whole blood. You put back the blood cells. The plasma gets dumped.
"But what of the leech?" we hear you cry. "Does it, too, still have a part to play in the removal of blood?" As it happens, yes.
Blood removal by leech is pretty useful during certain types of very delicate reparative surgery--such as when you're reattaching a fingertip or a scalp, says Dr. Randy Sherman, chief of the division of plastic and reconstructive surgery at USC's Keck School of Medicine.
Say you've reattached a finger and you've managed to repair the artery that runs into it. Say you can't repair the exit--the vein. Blood flows in, blood doesn't flow out. "In that case, we can lose the replantation because we haven't restored the complete circulation loop," Sherman says.
Enter the leech! Doctors stick it onto the replanted finger or scalp to suck up that extra blood so it doesn't end up pooling in the tissue.
The leech feeds until it's full, then drops off. The blood continues to ooze for a while (helped by the anticlotting chemicals in the leech saliva). Then on goes another leech.
Luckily, our veins are very good at finding alternate paths to shunt blood through our bodies, or the patient with the replanted finger would presumably have leeches stuck on him or her indefinitely. "Veins quite quickly, on the capillary level, will hook up and find each other," says Sherman. "Probably within a four-to six-day period."
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